feat(background_sizing): Added support for BackgroundSizing on Android

src/Uno.UI/Extensions/RectangleExtensions.Android.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using Android.Graphics;
 
 namespace Uno.UI
 {
@@ -11,6 +12,15 @@ internal static Android.Graphics.RectF ToRectF(this Windows.Foundation.Rect rect
 			return new Android.Graphics.RectF((float)rect.X, (float)rect.Y, (float)(rect.X + rect.Width), (float)(rect.Y + rect.Height));
         }
 
+		internal static Android.Graphics.Path ToPath(this Windows.Foundation.Rect rect)
+		{
+			var path = new Android.Graphics.Path();
+
+			path.AddRect(rect.ToRectF(), Path.Direction.Cw);
+
+			return path;
+		}
+
 		//Need this because the current implementation of Foundation.Rect's "IsEmpty"
 		// is not intended to convey information about the Rect's area.
 		internal static bool HasZeroArea(this Windows.Foundation.Rect rect)

src/Uno.UI/UI/Xaml/Controls/Border/Border.Android.cs

@@ -71,6 +71,7 @@ private void UpdateBorder(bool willUpdateMeasures)
 				_borderRenderer.UpdateLayer(
 					this,
 					Background,
+					BackgroundSizing,
 					BorderThickness,
 					BorderBrush,
 					CornerRadius,
@@ -93,6 +94,12 @@ protected override void OnBackgroundChanged(DependencyPropertyChangedEventArgs e
 			UpdateBorder();
 		}
 
+		private protected override void OnBackgroundSizingChanged(DependencyPropertyChangedEventArgs e)
+		{
+			// Don't call base: it's doing nothing
+			UpdateBorder();
+		}
+
 		partial void OnBorderThicknessChangedPartial(Thickness oldValue, Thickness newValue)
 		{
 			UpdateBorder();

src/Uno.UI/UI/Xaml/Controls/Border/BorderLayerRenderer.Android.cs

@@ -17,6 +17,7 @@
 using Uno.UI;
 using AndroidX.AppCompat.View;
 using System.Diagnostics;
+using Rect = Windows.Foundation.Rect;
 
 namespace Windows.UI.Xaml.Controls
 {
@@ -33,13 +34,15 @@ internal class BorderLayerRenderer
 		/// </summary>
 		/// <param name="view">The view to which we should add the layers</param>
 		/// <param name="background">The background brush of the border</param>
+		/// <param name="backgroundSizing">The background sizing (if drawn under border or not)</param>
 		/// <param name="borderThickness">The border thickness</param>
 		/// <param name="borderBrush">The border brush</param>
 		/// <param name="cornerRadius">The corner radius</param>
 		/// <param name="padding">The padding to apply on the content</param>
 		public void UpdateLayer(
 			FrameworkElement view,
 			Brush background,
+			BackgroundSizing backgroundSizing,
 			Thickness borderThickness,
 			Brush borderBrush,
 			CornerRadius cornerRadius,
@@ -71,7 +74,7 @@ public void UpdateLayer(
 				}
 
 				Action onImageSet = null;
-				var disposable = InnerCreateLayers(view, drawArea, background, borderThickness, borderBrush, cornerRadius, () => onImageSet?.Invoke());
+				var disposable = InnerCreateLayers(view, drawArea, background, backgroundSizing, borderThickness, borderBrush, cornerRadius, () => onImageSet?.Invoke());
 
 				// Most of the time we immediately dispose the previous layer. In the case where we're using an ImageBrush,
 				// and the backing image hasn't changed, we dispose the previous layer at the moment the new background is applied,
@@ -108,17 +111,18 @@ internal void Clear()
 		}
 
 		private static IDisposable InnerCreateLayers(BindableView view,
-			Windows.Foundation.Rect drawArea,
+			Rect drawArea,
 			Brush background,
+			BackgroundSizing backgroundSizing,
 			Thickness borderThickness,
 			Brush borderBrush,
 			CornerRadius cornerRadius,
-			Action onImageSet
-		)
+			Action onImageSet)
 		{
 			var disposables = new CompositeDisposable();
 
 			var physicalBorderThickness = borderThickness.LogicalToPhysicalPixels();
+			var isInnerBorderSizing = backgroundSizing == BackgroundSizing.InnerBorderEdge;
 			if (cornerRadius != 0)
 			{
 				if (view is UIElement uiElement && uiElement.FrameRoundingAdjustment is { } fra)
@@ -127,7 +131,10 @@ Action onImageSet
 					drawArea.Width += fra.Width;
 				}
 
-				var adjustedArea = drawArea.DeflateBy(physicalBorderThickness);
+				var adjustedArea =
+					isInnerBorderSizing
+						? drawArea.DeflateBy(physicalBorderThickness)
+						: drawArea;
 
 				using (var backgroundPath = cornerRadius.GetOutlinePath(adjustedArea.ToRectF()))
 				{
@@ -182,6 +189,13 @@ Action onImageSet
 				//We only need to set a background if the drawArea is non-zero
 				if (!drawArea.HasZeroArea())
 				{
+					var adjustedArea =
+						isInnerBorderSizing
+							? drawArea.DeflateBy(physicalBorderThickness)
+							: drawArea;
+
+					var outlinePath = adjustedArea.ToPath();
+
 					if (background is ImageBrush imageBrushBackground)
 					{
 						var setBackground = DispatchSetImageBrushAsBackground(view, imageBrushBackground, drawArea, onImageSet);
@@ -195,7 +209,7 @@ Action onImageSet
 					else
 					{
 						var fillPaint = background?.GetFillPaint(drawArea) ?? new Paint() { Color = Android.Graphics.Color.Transparent };
-						ExecuteWithNoRelayout(view, v => v.SetBackgroundDrawable(Brush.GetBackgroundDrawable(background, drawArea, fillPaint)));
+						ExecuteWithNoRelayout(view, v => v.SetBackgroundDrawable(Brush.GetBackgroundDrawable(background, drawArea, fillPaint, outlinePath)));
 					}
 					disposables.Add(() => ExecuteWithNoRelayout(view, v => v.SetBackgroundDrawable(null)));
 				}

src/Uno.UI/UI/Xaml/Controls/CalendarView/CalendarViewBaseItemChrome.uno.cs

@@ -92,7 +92,7 @@ private void UpdateChrome()
 				borderBrush = selectedBrush;
 			}
 
-			_borderRenderer.UpdateLayer(this, background, borderThickness, borderBrush, cornerRadius, default);
+			_borderRenderer.UpdateLayer(this, background, BackgroundSizing.InnerBorderEdge, borderThickness, borderBrush, cornerRadius, default);
 		}
 
 		private bool IsClear(Brush brush)

src/Uno.UI/UI/Xaml/Controls/ContentPresenter/ContentPresenter.Android.cs

@@ -80,6 +80,7 @@ private void UpdateBorder(bool willUpdateMeasures)
 				_borderRenderer.UpdateLayer(
 					this,
 					Background,
+					BackgroundSizing,
 					BorderThickness,
 					BorderBrush,
 					CornerRadius,

src/Uno.UI/UI/Xaml/Controls/Page/Page.Android.cs

@@ -41,6 +41,7 @@ private void UpdateBorder(bool willUpdateMeasures)
 				_borderRenderer.UpdateLayer(
 					this,
 					Background,
+					BackgroundSizing,
 					Thickness.Empty,
 					null,
 					CornerRadius.None,

src/Uno.UI/UI/Xaml/Controls/Panel/Panel.Android.cs

@@ -56,6 +56,7 @@ private void UpdateBorder(bool willUpdateMeasures)
 				_borderRenderer.UpdateLayer(
 					this,
 					Background,
+					BackgroundSizing,
 					BorderThickness,
 					BorderBrush,
 					CornerRadius,
@@ -110,6 +111,12 @@ protected override void OnBackgroundChanged(DependencyPropertyChangedEventArgs e
 			UpdateBorder();
 		}
 
+		private protected override void OnBackgroundSizingChanged(DependencyPropertyChangedEventArgs e)
+		{
+			// Don't call base: there's nothing there.
+			UpdateBorder();
+		}
+
 		protected override void OnBeforeArrange()
 		{
 			base.OnBeforeArrange();